Collar for sealing a battery module

ABSTRACT

The present disclosure relates to a battery module that includes a housing having a first absorptive material configured to absorb a laser emission, a cover having a second absorptive material configured to absorb the laser emission, and a collar configured coupled to the housing and coupled to the cover via a laser weld. The collar includes a transparent material configured to transmit the laser emission through the collar and toward the housing or the cover.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/146,781, filed Apr. 13, 2015,entitled “PLASTIC COVER TO HOUSING INTERFACE GEOMETRY AND MATERIALS FORLASER WELDING,” and U.S. Provisional Application Ser. No. 62/042,005,filed Aug. 26, 2014, entitled “LASER WELD OF A LITHIUM ION BATTERYSYSTEM,” which are hereby incorporated by reference in their entiretyfor all purposes. This application is related to U.S. Non-ProvisionalApplication No. XX/XXX,XXX, entitled “WELDING PROCESS FOR SEALING ABATTERY MODULE, ” filed on even date herewith, which is incorporatedherein by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to the field of batteries andbattery modules. More specifically, the present disclosure relates to alaser welding process for sealing a battery module.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described below. This discussion is believed to be helpful inproviding the reader with background information to facilitate a betterunderstanding of the various aspects of the present disclosure.Accordingly, it should be understood that these statements are to beread in this light, and not as admissions of prior art.

A vehicle that uses one or more battery systems for providing all or aportion of the motive power for the vehicle can be referred to as anxEV, where the term “xEV” is defined herein to include all of thefollowing vehicles, or any variations or combinations thereof, that useelectric power for all or a portion of their vehicular motive force. Forexample, xEVs include electric vehicles (EVs) that utilize electricpower for all motive force. As will be appreciated by those skilled inthe art, hybrid electric vehicles (HEVs), also considered xEVs, combinean internal combustion engine propulsion system and a battery-poweredelectric propulsion system, such as 48 Volt (V) or 130V systems. Theterm HEV may include any variation of a hybrid electric vehicle. Forexample, full hybrid systems (FHEVs) may provide motive and otherelectrical power to the vehicle using one or more electric motors, usingonly an internal combustion engine, or using both. In contrast, mildhybrid systems (MHEVs) disable the internal combustion engine when thevehicle is idling and utilize a battery system to continue powering theair conditioning unit, radio, or other electronics, as well as torestart the engine when propulsion is desired. The mild hybrid systemmay also apply some level of power assist, during acceleration forexample, to supplement the internal combustion engine. Mild hybrids aretypically 96V to 130V and recover braking energy through a belt or crankintegrated starter generator. Further, a micro-hybrid electric vehicle(mHEV) also uses a “Stop-Start” system similar to the mild hybrids, butthe micro-hybrid systems of a mHEV may or may not supply power assist tothe internal combustion engine and operate at a voltage below 60V. Forthe purposes of the present discussion, it should be noted that mHEVstypically do not technically use electric power provided directly to thecrankshaft or transmission for any portion of the motive force of thevehicle, but an mHEV may still be considered as an xEV since it does useelectric power to supplement a vehicle's power needs when the vehicle isidling with internal combustion engine disabled and recovers brakingenergy through an integrated starter generator. In addition, a plug-inelectric vehicle (PEV) is any vehicle that can be charged from anexternal source of electricity, such as wall sockets, and the energystored in the rechargeable battery packs drives or contributes to drivethe wheels. PEVs are a subcategory of EVs that include all-electric orbattery electric vehicles (BEVs), plug-in hybrid electric vehicles(PHEVs), and electric vehicle conversions of hybrid electric vehiclesand conventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as comparedto more traditional gas-powered vehicles using only internal combustionengines and traditional electrical systems, which are typically 12Vsystems powered by a lead acid battery. For example, xEVs may producefewer undesirable emission products and may exhibit greater fuelefficiency as compared to traditional internal combustion vehicles and,in some cases, such xEVs may eliminate the use of gasoline entirely, asis the case of certain types of EVs or PEVs.

As technology continues to evolve, there is a need to provide improvedpower sources, particularly battery modules, for such vehicles. Forexample, in traditional configurations, battery modules may includecomponents disposed in a sealed housing to shield the components fromenvironmental conditions and/or contaminants such as water, dirt, or thelike. Additionally, the sealed housing may include a vent path tocontrol emissions of substances produced within the battery module(e.g., battery cell effluent) into a surrounding environment. In somecases, the battery module may be sealed by a cover disposed over areceptacle region and/or a side cavity of the housing. However, in somecases, a seal between the housing and the cover may include cracks orgaps, thereby potentially exposing battery module components to thesurrounding environment, or vice versa. Therefore, it is now recognizedthat an improved seal between the housing and the cover is desired.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of certain embodiments and that theseaspects are not intended to limit the scope of this disclosure. Indeed,this disclosure may encompass a variety of aspects that may not be setforth below.

The present disclosure relates to a battery module that includes ahousing having a first absorptive material configured to absorb a laseremission, a cover having a second absorptive material configured toabsorb the laser emission, and a collar configured coupled to thehousing and coupled to the cover via a laser weld. The collar includes atransparent material configured to transmit the laser emission throughthe collar and toward the housing or the cover.

The present disclosure also relates to a battery module that includes ahousing having a first absorptive material configured to absorb a laseremission, a cover having a second absorptive material configured toabsorb the laser emission, and a collar coupled to the housing andcoupled to the cover via a laser weld. The collar includes a transparentmaterial configured to transmit the laser emission through the collarand toward the housing and the cover. The laser weld is formed by aprocess that includes disposing the cover over a receptacle region ofthe housing, disposing the collar around a first perimeter of thehousing and a second perimeter of the cover, directing a laser toward athird perimeter of the collar such that the laser is transmitted throughthe transparent material and is absorbed by the first absorptivematerial and the second absorptive material, heating the firstabsorptive material and the second absorptive material such that a firstportion of the first absorptive material increases in temperature andforms a first molten material and a second portion of the secondabsorptive material increases in temperature and forms a second moltenmaterial, and cooling the first molten material and the second moltenmaterial to adhere the housing to the collar and adhere the cover to thecollar.

The present disclosure also relates to a method for sealing a batterymodule that includes disposing a collar around a first perimeter of ahousing and a second perimeter of a cover, directing a laser toward athird perimeter of the collar such that the laser is transmitted througha transparent material of the collar and is absorbed by a firstabsorptive material of the housing and a second absorptive material ofthe cover, heating the first absorptive material and the secondabsorptive material such that a first portion of the first absorptivematerial increases in temperature and forms a first molten material anda second portion of the second absorptive material increases intemperature and forms a second molten material, and cooling the firstmolten material and the second molten material to adhere the housing tothe collar and adhere the cover to the collar.

DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a perspective view of a vehicle having a battery systemconfigured in accordance with present embodiments to provide power forvarious components of the vehicle, in accordance with an aspect of thepresent disclosure;

FIG. 2 is a cutaway schematic view of an embodiment of the vehicle andthe battery system of FIG. 1, in accordance with an aspect of thepresent disclosure;

FIG. 3 is an exploded perspective view of a battery module that may besealed using an improved laser welding technique, in accordance with anaspect of the present disclosure;

FIG. 4 is a perspective view of the battery module of FIG. 3 with anelectronics compartment cover and a cell receptacle region cover laserwelded to a housing, in accordance with an aspect of the presentdisclosure;

FIG. 5 is a perspective view of the battery module of FIGS. 3 and 4without the electronics compartment cover and the cell receptacle regioncover to show physical features that may facilitate a laser weld, inaccordance with an aspect of the present disclosure;

FIG. 6 is an expanded perspective view of a first protruding shelfdisposed on a perimeter of a electronics compartment of the housing ofFIGS. 3-5, in accordance with an aspect of the present disclosure;

FIG. 7 is a cross-sectional perspective view of the first protrudingshelf of FIG. 6, in accordance with an aspect of the present disclosure;

FIG. 8 is a cross-sectional perspective view of the electronicscompartment cover of FIG. 4 disposed adjacent to the first protrudingshelf of FIGS. 6 and 7, in accordance with an aspect of the presentdisclosure;

FIG. 9 is a close-up perspective view of a second protruding shelfdisposed on a second perimeter of a receptacle region of the housing ofFIGS. 3-5, in accordance with an aspect of the present disclosure;

FIG. 10 is a cross-sectional perspective view of the second protrudingshelf of FIG. 8, in accordance with an aspect of the present disclosure;

FIG. 11 is a cross-sectional perspective view of the receptacle regioncover of FIG. 4 disposed adjacent to the second protruding shelf ofFIGS. 9 and 10, in accordance with an aspect of the present disclosure;

FIG. 12 is a flow chart of a laser welding process that utilizesdifferent transmissivities and that may be utilized when the electronicscompartment cover includes a first transmissive material and/or when thecell receptacle region cover includes a second transmissive material, inaccordance with an aspect of the present disclosure;

FIG. 13 is a perspective view of the battery module of FIGS. 3-5 sealedusing a collar, in accordance with an aspect of the present disclosure;

FIG. 14 is a cross-sectional perspective view of a laser weld betweenthe collar of FIG. 13, a housing, and a cell receptacle region cover, inaccordance with an aspect of the present disclosure; and

FIG. 15 is a flow chart of a process that may be used to seal the cellreceptacle region cover to the housing of FIG. 14 using the collar ofFIGS. 13 and 14 when the cell receptacle region cover includes anabsorptive material, in accordance with an aspect of the presentdisclosure.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

The battery systems described herein may be used to provide power tovarious types of electric vehicles (xEVs) and other high voltage energystorage/expending applications (e.g., electrical grid power storagesystems). Such battery systems may include one or more battery modules,each battery module having a number of battery cells (e.g., lithium-ion(Li-ion) electrochemical cells) arranged and electrically interconnectedto provide particular voltages and/or currents useful to power, forexample, one or more components of an xEV. As another example, batterymodules in accordance with present embodiments may be incorporated withor provide power to stationary power systems (e.g., non-automotivesystems).

Battery modules may include a housing and a cover that encloseindividual components (e.g., individually sealed battery cells) of thebattery module and protect such components from conditions and/orcontaminants from a surrounding environment. Additionally, the housingand the cover may be sealed to one another to prevent inadvertentemissions of substances produced in the battery module (e.g., chemicalsand/or exhaust gas) into the surrounding environment. In some cases, theseal between the cover and the housing may have gaps and/or openingsthat expose sensitive components to contaminants and/or enable batterymodule emissions to be unintentionally released. However, it may bedesirable for the battery module to include a generally air-tight and/orwater-tight seal, such that components disposed in the housing may beprotected when the battery module is exposed to environments having highconcentrations of liquids and/or contaminants. Therefore, an improvedsealing technique may be desirable to provide an air-tight and/orwater-tight seal between the housing and the cover. It is now recognizedthat a laser weld between one or more covers and a housing of thebattery module (including shelf features to facilitate engagement andsealing) may form an air-tight and/or water-tight seal that eliminatesand/or substantially reduces gaps or openings between the housing andthe one or more covers.

In accordance with certain embodiments of the present disclosure, thehousing and the cover of the battery module may include materials thatare not traditionally used in laser welding processes. For example, thebattery module housing and the cover may include plastic. Moreover, insome cases, the housing and the cover of the battery module may includedifferent materials (e.g., metal), further complicating the formation ofa seal between the two components. In certain embodiments, the materialof the cover and the material of the housing may be selected based on anumber of considerations relating to their properties, such as theirstrength, weight, and conductivity. In certain embodiments, an assemblermay choose to utilize a cover with a transmissive material (e.g., amaterial more transmissive than the housing) that has a desired level oftransparency, thereby enabling a laser to pass through the cover (e.g.,a substantial amount of energy is not absorbed by the cover).Conversely, the housing may include an absorptive material (e.g., amaterial more absorptive than the cover) that absorbs energy (e.g.,light) from the laser welding process. The absorbed energy may cause atemperature of the absorptive material to increase, and thus, at least aportion of the absorptive material (e.g., a protruding shelf) may meltwhen the absorptive material reaches a certain temperature (e.g., amelting point of the absorptive material). When a portion of theabsorptive material melts, it may fill a gap or void between the housingand the cover, thus creating an air-tight and/or water-tight seal whenmolten absorptive material cools and re-hardens (e.g., re-solidifies).

However, in some cases, it may not be feasible to select the materialsof the housing and the cover based on their transmissive properties. Forexample, the material for the cover and the housing may be predeterminedby a supplier, and thus, the assembler (e.g., manufacturer of thebattery module) may not have the ability to select a desiredtransmissivity of the materials. For example, a cover purchased from asupplier may include a material that is absorptive, and thus, directlylaser welding such a cover to the housing may not be desirable (e.g.,the cover may absorb substantially all of the energy from the laser,thereby blocking formation of the laser weld between the cover and thehousing). In certain embodiments of the present disclosure, a collar maybe utilized to couple the cover to the housing and create asubstantially air-tight and/or water-tight seal. For example, the collarmay include a transmissive material (e.g., a material more transmissivethan the housing) that enables the laser to pass through the collar.Accordingly, energy from the laser may pass through the collar to boththe cover and to the housing. In certain embodiments, at least a firstportion of the housing and at least a second portion of the cover mayincrease in temperature upon exposure to the energy (e.g., light) fromthe laser, and thus, cause at least a portion of the collar to melt.Molten collar material may adhere to both the cover and the housing whencooled (e.g., re-solidified) to form the seal. In other embodiments, thefirst portion of the housing and the second portion of the cover maymelt and adhere to the collar when cooled (e.g., re-solidified) to formthe seal. In any case, a substantially air-tight and/or water-tight sealmay be formed between a cover having an absorptive material and thehousing via the collar.

Laser welding the cover to the housing may create a generally air-tightand/or water-tight seal such that the battery module components may beblocked from exposure to contaminants even when the battery module islocated in an environment having a high concentration of suchcontaminants (e.g., water, dirt). Accordingly, it is now recognized thatlaser welding the cover to the housing may produce a stronger and morerobust seal between the cover and the housing, which may enhance anoperating life of the battery module. Additionally, the stronger andmore robust seal may enhance a resistance of the battery module todamage caused by shock vibrations, drops, and/or crash testing.

To help illustrate the manner in which the present embodiments may beused in a system, FIG. 1 is a perspective view of an embodiment of avehicle 10 (e.g., an xEV), which may utilize a regenerative brakingsystem. Although the following discussion is presented in relation tovehicles with regenerative braking systems, the techniques describedherein are adaptable to other vehicles that capture/store electricalenergy with a battery, which may include electric-powered andgas-powered vehicles.

As discussed above, it would be desirable for a battery system 12 to belargely compatible with traditional vehicle designs. Accordingly, thebattery system 12 may be placed in a location in the vehicle 10 thatwould have housed a traditional battery system. For example, asillustrated, the vehicle 10 may include the battery system 12 positionedsimilarly to a lead-acid battery of a typical combustion-engine vehicle(e.g., under the hood of the vehicle 10).

A more detailed view of the battery system 12 is described in FIG. 2. Asdepicted, the battery system 12 includes an energy storage component 13coupled to an ignition system 14, an alternator 15, a vehicle console16, and optionally to an electric motor 17. Generally, the energystorage component 13 may capture/store electrical energy generated inthe vehicle 10 and output electrical energy to power electrical devicesin the vehicle 10.

In other words, the battery system 12 may supply power to components ofthe vehicle's electrical system, which may include radiator coolingfans, climate control systems, electric power steering systems, activesuspension systems, auto park systems, electric oil pumps, electricsuper/turbochargers, electric water pumps, heated windscreen/defrosters,window lift motors, vanity lights, tire pressure monitoring systems,sunroof motor controls, power seats, alarm systems, infotainmentsystems, navigation features, lane departure warning systems, electricparking brakes, external lights, or any combination thereof.Illustratively, in the depicted embodiment, the energy storage component13 supplies power to the vehicle console 16 and the ignition system 14,which may be used to start (e.g., crank) an internal combustion engine18.

Additionally, the energy storage component 13 may capture electricalenergy generated by the alternator 15 and/or the electric motor 17. Insome embodiments, the alternator 15 may generate electrical energy whilethe internal combustion engine 18 is running. More specifically, thealternator 15 may convert the mechanical energy produced by the rotationof the internal combustion engine 18 into electrical energy.Additionally or alternatively, when the vehicle 10 includes an electricmotor 17, the electric motor 17 may generate electrical energy byconverting mechanical energy produced by the movement of the vehicle 10(e.g., rotation of the wheels) into electrical energy. Thus, in someembodiments, the energy storage component 13 may capture electricalenergy generated by the alternator 15 and/or the electric motor 17during regenerative braking. As such, the alternator 15 and/or theelectric motor 17 are generally referred to herein as a regenerativebraking system.

To facilitate capturing and supplying electric energy, the energystorage component 13 may be electrically coupled to the vehicle'selectric system via a bus 19. For example, the bus 19 may enable theenergy storage component 13 to receive electrical energy generated bythe alternator 15 and/or the electric motor 17. Additionally, the bus 19may enable the energy storage component 13 to output electrical energyto the ignition system 14 and/or the vehicle console 16. Accordingly,when a 12 volt battery system 12 is used, the bus 19 may carryelectrical power typically between 8-18 volts.

Additionally, as depicted, the energy storage component 13 may includemultiple battery modules. For example, in the depicted embodiment, theenergy storage component 13 includes a lithium ion (e.g., a first)battery module 20 in accordance with present embodiments, and alead-acid (e.g., a second) battery module 22, where each battery module20, 22 includes one or more battery cells (e.g., individually sealedbattery cells). In other embodiments, the energy storage component 13may include any number of battery modules. Additionally, although thelithium ion battery module 20 and lead-acid battery module 22 aredepicted adjacent to one another, they may be positioned in differentareas around the vehicle. For example, the lead-acid battery module 22may be positioned in or about the interior of the vehicle 10 while thelithium ion battery module 20 may be positioned under the hood of thevehicle 10.

In some embodiments, the energy storage component 13 may includemultiple battery modules to utilize multiple different batterychemistries. For example, when the lithium ion battery module 20 isused, performance of the battery system 12 may be improved since thelithium ion battery chemistry generally has a higher coulombicefficiency and/or a higher power charge acceptance rate (e.g., highermaximum charge current or charge voltage) than the lead-acid batterychemistry. As such, the capture, storage, and/or distribution efficiencyof the battery system 12 may be improved.

To facilitate controlling the capturing and storing of electricalenergy, the battery system 12 may additionally include a control module24. More specifically, the control module 24 may control operations ofcomponents in the battery system 12, such as relays (e.g., switches)within the energy storage component 13, the alternator 15, and/or theelectric motor 17. For example, the control module 24 may regulate anamount of electrical energy captured/supplied by each battery module 20or 22 (e.g., to de-rate and re-rate the battery system 12), perform loadbalancing between the battery modules 20 and 22, determine a state ofcharge of each battery module 20 or 22, determine a temperature of eachbattery module 20 or 22, control voltage output by the alternator 15and/or the electric motor 17, and the like.

Accordingly, the control unit 24 may include one or more processor 26and one or more memory 28. More specifically, the one or more processor26 may include one or more application specific integrated circuits(ASICs), one or more field programmable gate arrays (FPGAs), one or moregeneral purpose processors, or any combination thereof. Additionally,the one or more memory 28 may include volatile memory, such as randomaccess memory (RAM), and/or non-volatile memory, such as read-onlymemory (ROM), optical drives, hard disc drives, or solid-state drives.In some embodiments, the control unit 24 may include portions of avehicle control unit (VCU) and/or a separate battery control module.

As discussed above, some components included in the battery module 20may be sensitive to conditions and/or contaminants (e.g., water, dirt,other debris) that may be present in a surrounding environment of thebattery module 20. Accordingly, it may be desirable to form an air-tightand/or water-tight seal between one or more covers and a housing of thebattery module 20 to prevent damage to the sensitive components.Additionally, the air-tight and/or water-tight seal may enablesubstances produced in the battery module (e.g., exhaust gas) to bedirected along a predetermined vent path, which may controllably emitsuch substances into a line specifically configured to release them intothe surrounding environment. Laser welding the one or more covers to thehousing of the battery module 20 in accordance with presently disclosedtechniques may form a more secure seal when compared to traditionalcoupling methods. Additionally, the seal formed using the presentlydisclosed laser welding process may be substantially air-tight and/orwater-tight. In certain embodiments, when the one or more covers includea transmissive material (e.g., a material more transmissive than thehousing), the one or more covers may be directly laser welded to thehousing. Conversely, a collar may be utilized to form the seal betweenthe one or more covers and the housing when the one or more coversinclude an absorptive material.

For example, FIG. 3 is an exploded perspective view of the batterymodule 20 that may be sealed using embodiments of the disclosed laserwelding technique. As shown in the illustrated embodiment, FIG. 3includes a housing 50, an electronics compartment cover 52, and a cellreceptacle region cover 54. Battery module components 56 (e.g.,electrochemical cells, electronics) may be disposed in a cell receptacleregion 58 of the housing 50 and/or in an electronics compartment 60 ofthe housing 50. Such battery module components 56 may enable the batterymodule 20 to produce and supply electrical current to a load (e.g., thexEV 10). For example, the battery module 20 may include one or moreindividually sealed electrochemical cells, each having at least one cellterminal. As used herein, an individually sealed electrochemical cellmay have a separate housing from the battery module 20 that encloses andseals all components (e.g., chemicals) of the electrochemical cell. Incertain embodiments, the at least one cell terminal of eachelectrochemical cell may be coupled to a bus bar. A plurality of suchbus bars may interconnect the electrochemical cells to one another aswell as to terminals of the battery module 20. For example, the batterymodule 20 may include a first module terminal 62 (e.g., positiveterminal) and a second module terminal 64 (e.g., negative terminal). Thefirst and second module terminals 62, 64 may be electrically coupled toa load and ultimately supply electrical power to the load (e.g., thexEV).

The electrochemical cells and other battery module components 56 (e.g.,electronics) may be sensitive to conditions and/or contaminants presentin a surrounding environment of the battery module 20. Accordingly, theelectronics compartment cover 52 and the cell receptacle region cover 54may be physically (e.g., permanently) coupled to the housing 50. Forexample, the electronics compartment cover 52 may be coupled to thehousing 50 such that the electronics compartment cover 52 substantiallycovers the electronics compartment 60 (e.g., forms an air-tight and/orwater-tight seal) and the cell receptacle region cover 54 may be coupledto the housing 50 such that the cell receptacle region cover 54substantially covers the cell receptacle region 58 (e.g., forms anair-tight and/or water-tight seal). In certain embodiments, theelectronics compartment cover 52 and/or the cell receptacle region cover54 may form a substantially air-tight and/or water-tight seal with thehousing 50. Therefore, the battery module components 56 may be protectedand/or blocked from exposure to any contaminants (e.g., water ormoisture) in the surrounding environment of the battery module 20. Toform the substantially air-tight and/or water-tight seal, a laser weldmay be formed between the electronics compartment cover 52 and thehousing 50 and/or between the cell receptacle region cover 54 and thehousing 50. A process for forming the substantially air-tight and/orwater-tight seal may depend at least on a material composition of thehousing 50, the electronics compartment cover 52, and the cellreceptacle region cover 54.

In certain embodiments, the electronics compartment cover 52 and thecell receptacle region cover 54 may each include a transmissive material(e.g., a transparent material that is more transmissive than a materialof the housing 50). For example, the electronics compartment cover 52may include a first transmissive material (e.g., a first transparentmaterial) that may allow the laser to pass through the electronicscompartment cover 52 without absorbing a substantial amount of theenergy. In other words, the first transmissive material (e.g., the firsttransparent material) may enable the laser to pass from a first surfaceof the electronics compartment cover 52 to a second surface of theelectronics compartment cover 52 without incurring a substantialincrease in temperature. In other embodiments, a first portion of theelectronics compartment cover 52 may include the first transmissivematerial, and a second portion of the electronics compartment cover 52may include an absorptive material or another material different fromthe first transmissive material. The first transmissive material mayinclude a polymeric material (e.g., polypropylene). For example, thepolymeric material may be transmissive black polypropylene. As usedherein, transmissive black polypropylene may be a polymeric materialthat includes a black colorant additive and has transmissive properties(e.g., allowing the laser to pass through the electronics compartmentcover 52 without absorbing a substantial amount of the energy).

Further, the first transmissive material may include one or morefillers. For example, the first transmissive material may includepolypropylene (e.g., black transmissive polypropylene) having a glassfiller. As used herein a glass filler may be glass particles that arehomogenously mixed with a base material (e.g., black transmissivepolypropylene). The glass filler may add structural reinforcement to thebase material (e.g., black transmissive polypropylene), therebyenhancing a strength of the base material. In certain embodiments, theglass filler may also reduce a transmissivity of a given material,thereby increasing an amount of energy that the material absorbs. Theamount of glass filler included in the base material (e.g., blacktransmissive polypropylene) may depend on a desired transmissivity ofthe first transmissive material and/or a wavelength of a laser that maybe used for the laser welding process. For example, a percent weight ofglass filler included in the first transmissive material may be between0% and 50%, between 10% and 40%, between 25% and 35%, or any combinationthereof. In other embodiments, any suitable filler or pigment may beutilized to enhance a structural integrity of the base material and/orto increase or decrease the transmissivity of the first transmissivematerial to the desired transmissivity.

In certain embodiments, the percent weight of the filler may beinversely proportional to the wavelength of the laser and/orproportional to the power (e.g., intensity) of the laser. For example,as the wavelength of the laser increases, the power of the laser (e.g.,energy output) decreases, and thus, it may be desirable to include alower percent weight of filler to increase transmissivity and enablemore energy to pass through the electronics compartment cover 52.Conversely, as the wavelength of the laser decreases, the power of thelaser (e.g., the energy output) may increase. Therefore, it may bedesirable to increase the percent weight of filler in the firsttransmissive material so that some energy is absorbed by the firsttransmissive material and an amount of energy passing through theelectronics compartment cover 52 may be substantially constantregardless of the operating wavelength and power of the laser.

In other embodiments, the first transmissive material may includepolyphenylene sulfide (PPS), nylon, or any combination thereof.Additionally, the PPS and/or the nylon may or may not include fillers(e.g., glass filler). In still further embodiments, the electronicscompartment cover 52 may include an absorptive material that may absorball, or substantially all, energy directed at the electronicscompartment cover 52. For example, when the laser is directed toward theelectronics compartment cover 52, the electronics compartment cover 52may absorb the energy emitted from the laser, and thus not direct asubstantial amount of energy toward the housing 50. Welding theelectronics compartment cover 52 to the housing 50 when the electronicscompartment cover 52 includes an absorptive material is discussed inmore detail herein with reference to FIGS. 12-15.

Additionally, the cell receptacle region cover 54 may include a secondtransmissive material (e.g., a second transparent material that is moretransmissive than the material of the housing 50). In certainembodiments, the second transmissive material may be the same as thefirst transmissive material. In other embodiments, the first and secondtransmissive materials may be different. For example, the secondtransmissive material (e.g., second transparent material) may allow thelaser to pass through the cell receptacle region cover 54 withoutabsorbing a substantial amount of the energy. In other words, the secondtransmissive material (e.g., second transparent material) may enableenergy to pass from a first surface of the cell receptacle region cover54 to a second surface of the cell receptacle region cover 54 withoutincurring a substantial increase in temperature. In other embodiments, afirst portion of the cell receptacle region cover 54 may include thesecond transmissive material, and a second portion of the cellreceptacle region cover 54 may include an absorptive material or anothermaterial different from the second transmissive material. The secondtransmissive material may include a polymeric material. For example, thepolymeric material may be transmissive black polypropylene.

Further, the second transmissive material may include one or morefillers. For example, the second transmissive material may includepolypropylene (e.g., black transmissive polypropylene) having the glassfiller. As discussed above, the glass filler may add structuralreinforcement to the base material (e.g., black transmissivepolypropylene), thereby enhancing a strength of the base material.Additionally, the glass filler may reduce a transmissivity of the secondtransmissive material, thereby increasing an amount of energy that thecell receptacle region cover 54 may absorb. The amount of glass fillerincluded in the base material (e.g., black transmissive polypropylene)of the cell receptacle region cover 54 may depend on a desiredtransmissivity of the second transmissive material, the wavelength ofthe laser, and/or the power (e.g., intensity) of the laser. For example,a percent weight of glass filler included in the second transmissivematerial may be between 0% and 50%, between 10% and 40%, between 25% and35%, or any combination thereof. In other embodiments, any suitablefiller or pigment may be utilized to enhance a structural integrity ofthe base material and/or increase or decrease the transmissivity of thesecond transmissive material to the desired transmissivity.

In other embodiments, the second transmissive material may includepolyphenylene sulfide (PPS), nylon, or any combination thereof.Additionally, the PPS and/or the nylon may or may not include fillers(e.g., glass filler). In still further embodiments, the cell receptacleregion cover 54 may include an absorptive material that may absorb all,or substantially all, energy directed at the cell receptacle regioncover 54. For example, when the laser is directed toward the cellreceptacle region cover 54, the cell receptacle region cover 54 mayabsorb the energy emitted from the laser, and thus not direct asubstantial amount of energy toward the housing 50. Welding the cellreceptacle region cover 54 to the housing 50 when the cell receptacleregion cover 54 includes an absorptive material is discussed in moredetail herein with reference to FIGS. 12-15.

In certain embodiments, the housing 50 may include an absorptivematerial (e.g., a material more absorptive than a material of theelectronics compartment cover 52 and/or a material of the cellreceptacle region cover 54). Accordingly, when the laser is directedtoward the housing 50, the housing 50 may be configured to absorb theenergy emitted from the laser. In certain embodiments, the absorption ofenergy may cause a temperature of the housing 50 to increase, which mayeventually cause at least a portion (e.g., a protruding shelf) of thehousing 50 to melt.

In certain embodiments, the absorptive material may be a polymericmaterial (e.g., polypropylene). Additionally, the absorptive materialmay include one or more fillers that may enhance absorptive propertiesof the absorptive material. For example, the absorptive material may bepolypropylene that includes a carbon black filler. As used herein, acarbon black filler may be a black pigment that increases absorptivequalities of a base material (e.g., polypropylene). In certainembodiments, a weight percent of carbon black in the base material(e.g., polypropylene) may be between 0% and 10%, between 0.01% and 1%,between 0.1% and 0.5%, or any combination thereof. The amount of fillerincluded in the absorptive material may depend on the wavelength of thelaser, a power (e.g., energy output) of the laser, and/or thetransmissivity of the electronics compartment cover 52 and/or the cellreceptacle region cover 54. When too much carbon black filler isutilized, the desirable qualities of the absorptive material (e.g.,polymeric material) may diminish, and when too little carbon blackfiller is included, the absorptive material may not absorb a sufficientamount of energy. Therefore, it should be understood that there is adelicate balance regarding an amount of carbon black filler included inthe base material (e.g., polypropylene). Additionally, in certainembodiments, the carbon black filler may be included in the basematerial only at a predetermined weld spot (e.g., where the laser willbe directed). In other embodiments, the carbon black filler may be mixedhomogenously throughout the base material. In still further embodiments,the absorptive material of the housing 50 may include PPS, nylon, or anycombination thereof.

As discussed above, the laser welding process may depend on thematerials included in the housing 50, the electronics compartment cover52, and/or the cell receptacle region cover 54. For example, when theelectronics compartment cover 52 and/or the cell receptacle region cover54 include a material that has a relatively high transmissivity (e.g., amaterial more transmissive than the housing 50), it may be desirable todirectly laser weld the electronics compartment cover 52 and/or the cellreceptacle region cover 54 to the housing 50. However, when theelectronics compartment cover 52 and/or the cell receptacle region cover54 include an absorptive material and/or a material having a relativelylow transmissivity, a collar may be utilized to form the seal betweenthe electronics compartment cover 52 and the housing 50 and/or betweenthe cell receptacle region cover 54 and the housing 50. In any case, theelectronics compartment cover 52 and the cell receptacle region cover 54may be sealed to the housing 50 such that the battery module 20 issubstantially air-tight and/or water-tight.

For example, FIG. 4 illustrates a perspective view of the battery module20 with the electronics compartment cover 52 and the cell receptacleregion cover 54 laser welded to the housing 50. As shown in theillustrated embodiment of FIG. 4, no gaps or spaces are formed betweenthe electronics compartment cover 52 and the housing 50 and/or the cellreceptacle region cover 54 and the housing 50. In other words, the cellreceptacle region 58 and the electronics compartment 60 are completelycovered by the cell receptacle region cover 54 and the electronicscompartment cover 52, respectively. Therefore, the battery module 20 maybe substantially air tight and/or water-tight, which may enhance alifetime of the battery module 20.

In certain embodiments, the housing 50 of the battery module 20 mayinclude physical features that may facilitate a laser weld between theelectronics compartment cover 52 and the housing 50 and/or the cellreceptacle region cover 54 and the housing 50. For example, FIG. 5 is aperspective view of the battery module 20 of FIG. 4 without theelectronics compartment cover 52 and the cell receptacle region cover 54to make such physical features visible. As shown in the illustratedembodiment of FIG. 5, a first perimeter 80 of the electronicscompartment 60 includes a first protruding shelf 82. Additionally, asecond perimeter 84 of the cell receptacle region 58 includes a secondprotruding shelf 86. In certain embodiments, the first and secondprotruding shelves 82, 86 may be utilized to facilitate welding theelectronics compartment cover 52 and/or the cell receptacle region cover54 to the housing 50. For example, a weld spot of a laser may bedirected toward the first protruding shelf 82 and/or the secondprotruding shelf 86 during the laser welding process. Accordingly, thefirst protruding shelf 82 and/or the second protruding shelf 86 may meltto form a molten material that may fill a gap or void between thehousing 50 and the electronics compartment cover 52 and/or the housing50 and the cell receptacle region cover 54. Additionally, the firstprotruding shelf 82 and/or the second protruding shelf 86 may include arelatively large surface area to place the electronics compartment cover52 and/or the cell receptacle region cover 54 against.

In certain embodiments, the first protruding shelf 82 and/or the secondprotruding shelf 86 may include the same material as the housing 50(e.g., the absorptive material). In other embodiments, the firstprotruding shelf 82 and the second protruding shelf 86 may include theabsorptive material, and any remaining portions of the housing 50 mayinclude a different material (e.g., the first and/or second transmissivematerial or a second absorptive material). Further, the first protrudingshelf 82 and/or the second protruding shelf 86 may be integrated intothe housing 50 (e.g., molded into the housing 50). For example, thefirst protruding shelf 82 and/or the second protruding shelf 86 may beformed by etching or cutting out a portion of the first perimeter 80and/or the second perimeter 84. In other embodiments, the firstprotruding shelf 82 and/or the second protruding shelf 86 may beseparate components from the housing 50 that are coupled to the housing50 (e.g., via an adhesive) during assembly.

FIG. 6 is an expanded perspective view of the first protruding shelf 82disposed on the first perimeter 80 of the electronics compartment 60. Incertain embodiments, the first protruding shelf 82 may extend along theentire first perimeter 80 of the electronics compartment 60. In otherembodiments, the first protruding shelf 82 may extend along only aportion of the first perimeter 80. As shown in the illustratedembodiment of FIG. 6, the first protruding shelf 82 may extend a firstdistance 87 from the first perimeter 80 of the electronics compartment60. In certain embodiments, the first distance 87 may be predeterminedbased on a size of the gap or void that forms between the housing 50 andthe electronics compartment cover 52 before the laser weld is formed(see FIG. 8). For example, as a size of the gap or void between thehousing 50 and the electronics compartment cover 52 increases, the firstdistance 87 may also increase, such that more molten material may beformed to fill in the gap or void. Similarly, as the size of the gap orvoid between the housing 50 and the electronics compartment cover 52decreases, the first distance 87 may also decrease because less moltenmaterial may be utilized to fill the gap or void. Additionally, incertain embodiments, the first distance 87 may be substantially constantalong the first perimeter 80 of the electronics compartment 60. In otherembodiments, the first distance 87 may vary along the first perimeter 80in proportion to a size of the gap or void between the housing 50 andthe electronics compartment cover 52. In still further embodiments, thefirst distance 87 may vary along the first perimeter 80 in proportion toa groove of the first protruding shelf 82 (see FIG. 7).

As shown in the illustrated embodiment of FIG. 6, the first protrudingshelf 82 includes relatively sharp edges and/or corners that correspondto edges and corners around the first perimeter 80 of the electronicscompartment 60. However, it should be noted that the first protrudingshelf 82 may include edges and/or corners with any suitable shape (e.g.,rounded edges and/or corners).

Additionally, the first protruding shelf 82 may include a protrusion 88(e.g., a first protrusion), a groove 89 (e.g., a first groove), and alip 90 (e.g., a first lip), as shown in FIG. 7. For example, the firstprotruding shelf 82 may include the protrusion 88 that extends the firstdistance 87 from the lip 90. In certain embodiments, the laser may bedirected toward the protrusion 88, thereby causing the protrusion 88 tomelt. As the protrusion 88 melts, molten material may collect in thegroove 89, which may prevent molten material from spilling over the lip90. In certain embodiments, the groove 89 may include a semi-circularshaped cross-section that enables molten material to collect in thegroove 89 and to contact the electronics compartment cover 52. In otherembodiments, the groove 89 may include any suitable shape to enable themolten material to collect in the groove 89 and to contact theelectronics compartment cover 52. Therefore, when the molten materialcools and re-hardens (e.g., re-solidifies), the electronics compartmentcover 52 may adhere to the housing 50. In certain embodiments, themolten material may fill any gaps and/or voids between the electronicscompartment cover 52 and the housing 50, thereby forming a substantiallyair-tight and/or water-tight seal.

In certain embodiments, the protrusion 88 of the first protruding shelf82 may be configured to provide a surface for the electronicscompartment cover 52 to contact prior to formation of the laser weld.For example, FIG. 8 is a cross-sectional perspective view of theelectronics compartment cover 52 adjacent to the protrusion 88 of thefirst protruding shelf 82. As shown in the illustrated embodiment ofFIG. 8, the protrusion 88 of the first protruding shelf 82 is disposedagainst the electronics compartment cover 52; however, the electronicscompartment cover 52 does not interlock with the first protruding shelf82 and/or another feature of the housing 50 (e.g., via an interferencefit). A laser weld may be performed to couple the electronicscompartment cover 52 to the housing 50. Accordingly, in certainembodiments, a laser may be directed at a third perimeter 91 of theelectronics compartment cover 52, such that a weld spot of the laser isaligned with the first protruding shelf 82. When the electronicscompartment cover 52 includes the first transmissive material, the lasermay be directed through the third perimeter 91 of the electronicscompartment cover 52 and toward the protrusion 88 of the firstprotruding shelf 82. Accordingly, when the material of the protrusion 88reaches a melting point, molten material may collect in the groove 89 aswell as fill a gap between the electronics compartment cover 52 and thehousing 50. The laser may then be removed (or turned off) such that themolten material may cool and re-harden (e.g., re-solidify). Uponre-hardening, the housing 50 may adhere to the electronics compartmentcover 52, thereby eliminating and/or substantially reducing any gapsand/or openings that may form between the housing 50 and the electronicscompartment cover 52.

As discussed above, the second perimeter 84 of the cell receptacleregion 58 may also include the second protruding shelf 86. For example,FIG. 9 is an expanded perspective view of the second protruding shelf 86disposed on the second perimeter 84 of the cell receptacle region 58 ofthe housing 50. In certain embodiments, the second protruding shelf 86may extend along the entire second perimeter 84 of the cell receptacleregion 58. In other embodiments, the second protruding shelf 86 mayextend along only a portion of the second perimeter 84. As shown in theillustrated embodiment of FIG. 9, the second protruding shelf 86 mayextend a second distance 92 from the second perimeter 84 of the cellreceptacle region 58. In certain embodiments, the second distance 92 maybe predetermined based on a size of the gap or void that forms betweenthe housing 50 and the cell receptacle region cover 54 before the laserweld is formed. For example, as a size of the gap or void between thehousing 50 and the cell receptacle region cover 54 increases, the seconddistance 92 may also increase, such that more molten material may beformed to fill in the gap or void. Similarly, as the size of the gap orvoid between the housing 50 and the cell receptacle region cover 54decreases, the second distance 92 may also decrease because less moltenmaterial may be utilized to fill the gap or void. Additionally, incertain embodiments, the second distance 92 may be substantiallyconstant along the second perimeter 84 of the cell receptacle region 58.In other embodiments, the second distance 92 may vary along the secondperimeter 84 in proportion to a size of the gap or void between thehousing 50 and the cell receptacle region cover 54. In still furtherembodiments, the second distance 92 may vary along the second perimeter84 in proportion to a second groove of the second protruding shelf 86(see FIG. 10).

As shown in the illustrated embodiment of FIG. 9, the second protrudingshelf 86 includes relatively sharp edges and/or corners that correspondto edges and corners around the second perimeter 84 of the cellreceptacle region 58. However, it should be noted that the secondprotruding shelf 86 may include edges and/or corners with any suitableshape (e.g., rounded edges and/or corners).

Additionally, the second protruding shelf 86 may include a secondprotrusion 93, a second groove 94, and a second lip 95, as shown in FIG.10. For example, the second protruding shelf 86 may include the secondprotrusion 93 that extends the second distance 92 from the second lip95. In certain embodiments, the laser may be directed toward the secondprotrusion 93, thereby causing the second protrusion 93 to melt. As thesecond protrusion 93 melts, molten material may collect in the secondgroove 94, which may prevent molten material from spilling over thesecond lip 95. In certain embodiments, the second groove 94 may includea semi-circular shaped cross-section that enables molten material tocollect in the second groove 94 and to contact the cell receptacleregion cover 54. In other embodiments, the second groove 94 may includeany suitable shape to enable the molten material to collect in thesecond groove 94 and to contact the cell receptacle region cover 54.When the molten material cools and re-hardens (e.g., re-solidifies), thecell receptacle region cover 54 may adhere to the housing 50. In certainembodiments, the molten material may fill any gaps and/or voids betweenthe cell receptacle region cover 54 and the housing 50, thereby forminga substantially air-tight and/or water-tight seal.

In certain embodiments, the second protrusion 93 of the secondprotruding shelf 86 may be configured to provide a contact surface forthe cell receptacle region cover 54 prior to formation of the laserweld. For example, FIG. 11 is a cross-sectional perspective view of thecell receptacle region cover 54 adjacent to the second protrusion 93 ofthe second protruding shelf 86. As shown in the illustrated embodimentof FIG. 11, the second protrusion 93 of the second protruding shelf 86is disposed against the cell receptacle region cover 54; however, thecell receptacle region cover 54 does not interlock with the secondprotruding shelf 86 and/or another feature of the housing 50 (e.g., viaan interference fit). A laser weld may be performed to couple the cellreceptacle region cover 54 to the housing 50. Accordingly, in certainembodiments, a laser may be directed at a fourth perimeter 96 of thecell receptacle region cover 54, such that a weld spot of the laser isaligned with the second protruding shelf 86. When the cell receptacleregion cover 54 includes the second transmissive material, the laser maybe directed through the fourth perimeter 96 of the cell receptacleregion cover 54 and toward the second protrusion 93 of the secondprotruding shelf 86. Accordingly, when the material of the secondprotrusion 93 reaches a melting point, molten material may collect inthe second groove 94 and fill a gap between the cell receptacle regioncover 54 and the housing 50. The laser may then be removed (or turnedoff) such that the molten material may cool and re-harden (e.g.,re-solidify). Upon re-hardening, the housing 50 may adhere to the cellreceptacle region cover 54, thereby eliminating and/or substantiallyreducing any gaps and/or openings that may form between the housing 50and the cell receptacle region cover 54.

As discussed above, when the electronics compartment cover 52 includesthe first transmissive material and/or when the cell receptacle regioncover 54 includes the second transmissive material, a laser weldingprocess may be utilized that directly welds the electronics compartmentcover 52 and/or the cell receptacle region cover 54 to the housing 50(e.g., via the first and/or second protruding shelves 82, 86). Forexample, FIG. 12 is a flow chart 100 for a laser welding process thatmay be utilized when the electronics compartment cover 52 includes thefirst transmissive material and/or when the cell receptacle region cover54 includes the second transmissive material.

At block 102, the electronics compartment cover 52 and/or the cellreceptacle region cover 54 may be disposed against the housing 50. Incertain embodiments, a clamp may be utilized to press the electronicscompartment cover 52 and/or the cell receptacle region cover 54 towardthe housing 50, thereby securing the electronics compartment cover 52and/or the cell receptacle region cover 54 during the welding process.As used herein, the clamp may be a device configured to substantiallyexert a biasing force on the third perimeter 91 of the electronicscompartment cover 52 and/or the fourth perimeter 96 of the cellreceptacle region cover 54 toward the housing 50. Such biasing force mayensure that the gap and/or void between the electronics compartmentcover 52 and the housing 50 and/or the cell receptacle region cover 54and the housing 50 remains substantially constant throughout the weldingprocess. Additionally, the clamp may prevent movement of the electronicscompartment cover 52 and/or the cell receptacle region cover 54 duringthe welding process. In some cases, movement of the electronicscompartment cover 52 and/or the cell receptacle region cover 54 may beundesirable because it may result in a weaker laser weld.

At block 104, the laser may be directed toward the third perimeter 91 ofthe electronics compartment cover 52 and/or the fourth perimeter 96 ofthe cell receptacle region cover 54. In certain embodiments, the laser,the third perimeter 91, and the first protruding shelf 82 (e.g., theprotrusion 88) may be in substantial alignment when laser welding theelectronics compartment cover 52 to the housing 50. Similarly, thelaser, the fourth perimeter 96, and the second protruding shelf 86(e.g., the second protrusion 93) may be in substantial alignment whenlaser welding the cell receptacle region cover 54 to the housing 50.Accordingly, when the laser is directed toward the third perimeter 91and/or the fourth perimeter 96, the laser may be transmitted through thefirst transmissive material of the electronics compartment cover 52and/or the second transmissive material of the cell receptacle regioncover 54. Therefore, the energy (e.g., light) from the laser may bereceived and absorbed by the protrusion 88 of the first protruding shelf82 (e.g., that includes the absorptive material) and/or the secondprotrusion 93 of the second protruding shelf 86 (e.g., that includes theabsorptive material).

In certain embodiments, the laser may be directed toward the thirdperimeter 91 and/or the fourth perimeter 96 by passing the laser overthe third perimeter 91 and/or the fourth perimeter 96 a predeterminednumber of times. For example, the laser may be directed around the thirdperimeter 91 and/or the fourth perimeter 96 between 1 and 10 times,between 2 and 8 times, between 5 and 6 times, or any suitable number oftimes to enable the absorptive material of the first protruding shelf 82(e.g., the protrusion 88) and/or the second protruding shelf 86 (e.g.,the second protrusion 93) to melt.

Additionally, the laser may be angled with respect to a first surface ofthe electronics compartment cover 52 and/or a second surface of the cellreceptacle region cover 54. For example, the laser may not besubstantially perpendicular to the first surface of the electronicscompartment cover 52 when laser welding the electronics compartmentcover 52 to the housing 50. Accordingly, the laser may be positionedsuch that a maximum amount of energy (e.g., light) from the laser may bereceived and/or absorbed by the first protruding shelf 82. Additionally,the laser may not be substantially perpendicular to the second surfaceof the cell receptacle region cover 54 when laser welding the cellreceptacle region cover 54 to the housing 50. Rather, the laser may beangled with respect to the second surface of the cell receptacle regioncover 54. Accordingly, the laser may be directed to the secondprotruding shelf 86 at an angle that enables a desired amount oftemperature increase of the second protruding shelf 86 (e.g., the secondprotrusion 93).

At block 106, the laser transmitted toward the first protruding shelf 82and/or the second protruding shelf 86 may cause the protrusion 88 of thefirst protruding shelf 82 (e.g., having the absorptive material) and/orthe second protrusion 93 of the second protruding shelf 86 (e.g., havingthe thermally absorptive material) to increase in temperature. As thetemperature of the protrusion 88 and/or the second protrusion 93increases, the absorptive material may begin to melt to form a moltenmaterial. Accordingly, the molten material may collect in the groove 89and/or the second groove 94 and fill a gap between the electronicscompartment cover 52 and the housing 50 and/or a gap between the cellreceptacle region cover 54 and the housing 50.

At block 108, the molten material may be cooled when the laser is nolonger directed toward the third perimeter 91 and/or the fourthperimeter 96 (e.g., when the laser is no longer incident on the thirdperimeter 91 and/or the fourth perimeter 96 and/or when the laser isturned off). Because the molten material may fill the gap between theelectronics compartment cover 52 and the housing 50 and/or the gapbetween the cell receptacle region cover 54 and the housing 50, themolten material may cause the electronics compartment cover 52 and/orthe cell receptacle region cover 54 to adhere to the housing 50 when themolten material re-hardens (e.g., re-solidifies). Accordingly, theelectronics compartment cover 52 and/or the cell receptacle region cover54 may be coupled to the housing 50, and gaps (e.g., substantially allgaps) or openings between the electronics compartment cover 52 and thehousing 50 and/or between the cell receptacle region cover 54 and thehousing 50 may be eliminated or substantially reduced.

As discussed above, the electronics compartment cover 52 may not includethe first transmissive material and/or the cell receptacle region cover54 may not include the second transmissive material (e.g., when theelectronics compartment cover 52 and/or the cell receptacle region cover54 are purchased from a supplier). In accordance with certainembodiments of the present disclosure, when the electronics compartmentcover 52 and/or the cell receptacle region cover 54 include anabsorptive material, a collar may be used to couple the electronicscompartment cover 52 and/or the cell receptacle region cover 54 to thehousing 50. The collar may also substantially eliminate and/or reduceany gaps or openings between the electronics compartment cover 52 andthe housing 50 and/or between the cell receptacle region cover 54 andthe housing 50 to form a substantially air-tight and/or water-tightseal. Additionally, the collar may be utilized to couple the electronicscompartment cover 52 to the housing 50 and/or the cell receptacle regioncover 54 to the housing 50 even when the electronics compartment cover52 includes the first transmissive material and/or the cell receptacleregion cover 54 includes the second transmissive material. In certainembodiments, it may be desirable to utilize the collar because the laserweld between a cover of the battery module (e.g., the electronicscompartment cover 52 and/or the cell receptacle region cover 54) and thehousing 50 may be broken without substantially damaging the cover and/orthe housing 50 (e.g., thereby facilitating servicing of the batterymodule 20).

For example, FIG. 13 is a perspective view of an embodiment of thebattery module 20 sealed using a collar 120. For simplicity, thefollowing discussion focuses on coupling the cell receptacle regioncover 54 to the housing 50 utilizing the collar 120. However, it shouldbe noted that the electronics compartment cover 52 discussed above withrespect to FIGS. 3-11 may also be coupled to the housing 50 using thecollar 120. As shown in the illustrated embodiment of FIG. 13, thecollar 120 is disposed around an entire first perimeter 122 of thehousing 50, which also corresponds to a second perimeter 124 of the cellreceptacle region cover 54. Accordingly, the collar 120 may seal thecell receptacle region cover 54 to the housing 50 without leaving anygaps and/or openings, such that the seal is substantially air-tightand/or water-tight.

In certain embodiments, the collar 120 may include a transmissivematerial (e.g., a transparent material that is more transmissive thanthe housing 50 and/or the cell receptacle region cover 54). For example,the collar 120 may include a clear polymeric material that may allowtransmission of laser energy (e.g., light) to pass through the collar120 without absorbing a substantial amount of the laser energy. In otherwords, the transmissive material (e.g., the transparent material) mayenable a laser emission to pass from a first surface (e.g., an outersurface) of the collar 120 to a second surface (e.g., a surfacepositioned against the housing 50 and the cell receptacle region cover54) of the collar 120 without increasing a temperature of the collar120. In certain embodiments, the transmissive material may include clearpolypropylene. In other embodiments, the transmissive material may betransmissive black polypropylene.

Further, the transmissive material of the collar 120 may include one ormore fillers. For example, the collar 120 may include polypropylene(e.g., black transmissive polypropylene) that has a glass filler. Theglass filler may add structural reinforcement to the base material(e.g., black transmissive polypropylene), thereby enhancing a strengthof the base material. In certain embodiments, the glass filler may alsoreduce a transmissivity of the collar 120, thereby increasing an amountof thermal energy that the collar 120 may absorb. The amount of fillerincluded in the transmissive material of the collar 120 may depend on adesired transmissivity of the collar 120 and/or a wavelength of a laserthat may be used for the laser welding process. For example, a percentweight of glass filler included in the collar 120 may be between 0% and50%, between 10% and 40%, between 25% and 35%, or any combinationthereof.

In certain embodiments, the weight percent of the glass filler may beinversely proportional to the wavelength and/or proportional to thepower of the laser. For example, as the wavelength of the laserincreases, the power of the laser (e.g., energy output) decreases, andthus, it may be desirable to include a lower percent weight of filler toincrease transmissivity and enable more energy to pass through thecollar 120. Conversely, as the wavelength of the laser decreases, thepower of the laser (e.g., the energy output) may increase. Therefore, itmay be desirable to increase the percent weight of filler in the collar120 such that a portion of the energy is absorbed by the transmissivematerial of the collar 120 and an amount of energy passing through thecollar 120 may be substantially constant.

In other embodiments, the transmissive material of the collar 120 mayinclude polyphenylene sulfide (PPS), nylon, or any combination thereof.Additionally, the PPS and/or the nylon may or may not include fillers.

Additionally, the cell receptacle region cover 54 and/or the housing 50may include an absorptive material (e.g., a material more absorptivethan the collar 120). For example, the cell receptacle region cover 54and/or the housing 50 may include the absorptive material having thesame material properties as described above. Accordingly, when the laseris directed toward the housing 50 and/or the cell receptacle regioncover 54, the housing 50 and/or the cell receptacle region cover 54 maybe configured to absorb the energy emitted from the laser. Additionally,the cell receptacle region cover 54 and/or the housing may include ametallic material that may also be configured to absorb energy (e.g.,light) emitted from the laser. In certain embodiments, the absorption ofenergy may cause a temperature of the housing 50 and/or the cellreceptacle region cover 54 to increase. In certain embodiments, theincrease in temperature of the housing 50 and the cell receptacle regioncover 54 may cause a portion of the collar 120 to melt, thereby causingthe housing 50 to adhere to the collar 120 (e.g., when the molten potionof the collar 120 re-hardens) and the cell receptacle region cover 54 toadhere to the collar (e.g., when the molten potion of the collar 120re-hardens). In other embodiments, the increase in temperature of thehousing 50 and/or the cell receptacle region cover 54 may cause a firstportion of the housing 50 and/or a second portion of the cell receptacleregion cover 54 to melt. Accordingly, the first portion and/or thesecond portion may cause the housing 50 and/or the cell receptacleregion cover 54 to adhere to the collar 120 (e.g., when the firstportion and/or the second portion re-harden).

Additionally, the collar 120 may include physical features that mayfacilitate coupling the cell receptacle region cover 54 to the housing50. For example, FIG. 14 is a cross-sectional perspective view of alaser weld between the collar 120, the housing 50, and the cellreceptacle region cover 54. As shown in the illustrated embodiment ofFIG. 14, the collar 120 includes a staircase configuration (e.g., astepped geometry) such that the collar 120 directly contacts the cellreceptacle region cover 54 and the housing 50. For example, a first step126 of the collar 120 may be configured to contact the housing 50 and asecond step 128 of the collar 120 may be configured to contact the cellreceptacle region cover 54. Accordingly, when laser welding the cellreceptacle region cover 54 to the housing 50, the laser may pass throughthe first step 126 toward the housing 50, thereby increasing thetemperature of the housing 50. As discussed above, in certainembodiments, increasing the temperature of the housing 50 may cause thefirst step 126 of the collar 120 to melt and form a molten material. Inother embodiments, increasing the temperature of the housing may causethe first portion of the housing 50 to melt to form a molten material.Similarly, the laser may pass through the second step 128 toward thecell receptacle region cover 54, thereby increasing the temperature ofthe cell receptacle region cover 54. In certain embodiments, increasingthe temperature of the cell receptacle region cover 54 may cause thesecond step 128 to melt and form a molten material. In otherembodiments, increasing the temperature of the cell receptacle regioncover 54 may cause the second portion of the cell receptacle regioncover 54 to melt and form the molten material. In any case, the moltenmaterial may cause both the housing 50 and the cell receptacle regioncover 54 to adhere to the collar 120. Accordingly, the housing 50 andthe cell receptacle region cover 54 may be coupled to one another viathe collar 120.

The seal between the housing 50, the cell receptacle region cover 54,and the collar 120 may be substantially air-tight and/or water-tightbecause the molten material may fill any gaps and/or voids between thehousing 50 and the collar 120 and/or between the cell receptacle regioncover 54 and the collar 120. Since the collar 120 extends along theentire first perimeter 122 and the entire second perimeter 124, gapsand/or voids between the cell receptacle region cover 54 and the housing50 may be substantially eliminated or reduced. Laser welding the cellreceptacle region cover 54 to the housing 50 when the cell receptacleregion cover 54 includes an absorptive material may thus produce anenhanced seal between the cell receptacle region cover 54 and thehousing 50 when the collar 120 is utilized.

For example, FIG. 15 is a flow chart 140 of a process for sealing thecell receptacle region cover 54 to the housing 50 using the collar 120.At block 142, the collar 120 is disposed around the first perimeter 122of the housing 50 and the second perimeter 124 of the cell receptacleregion cover 54. Accordingly, the first step 126 of the collar 120 maydirectly contact the housing 50 and the second step 128 of the collar120 may directly contact the cell receptacle region cover 54.

At block 144, a laser may be directed toward a third perimeter of thecollar 120. In certain embodiments, the laser, the third perimeter ofthe collar 120, the first perimeter 122 of the housing 50, and thesecond perimeter 124 of the cell receptacle region cover 54 may be insubstantial alignment. Accordingly, when the laser is directed towardthe third perimeter, the laser may be transmitted through thetransparent material of the collar 120 toward the housing 50 and thecell receptacle region cover 54. Therefore, energy from the laser may beabsorbed by a first absorptive material of the housing 50 and/or asecond absorptive material of the cell receptacle region cover 54. Inother embodiments, the laser may be rotated and/or moved in a sinusoidalmotion such that the laser contacts both the housing 50 and the cellreceptacle region cover 54.

In certain embodiments, the laser may be directed toward the thirdperimeter by passing the laser over the third perimeter a predeterminednumber of times. For example, the laser may be directed around the thirdperimeter between 1 and 10 times, between 2 and 8 times, between 5 and 6times, or any suitable number of times that may enable the firstabsorptive material of the housing 50 and the second absorptive materialof the cell receptacle region cover 54 to melt. Alternatively oradditionally, the increase in temperature of the housing 50 and the cellreceptacle region cover 54 may cause the collar 120 to melt over theperimeters 122, 124.

Additionally, the laser may be angled with respect to a surface 145 (seeFIG. 14) of the collar 120. For example, the laser may not besubstantially perpendicular to the surface 145 of the collar 120.Accordingly, the laser may be positioned such that a maximum amount ofenergy (e.g., light) from the laser may be received and/or absorbed bythe housing 50 and the cell receptacle region cover 54.

At block 146, absorption of the laser by the housing 50 and the cellreceptacle region cover 54 may cause a first portion of the housing 50(e.g., the housing 50 includes the first absorptive material) and asecond portion of the cell receptacle region cover 54 (e.g., the cellreceptacle region cover 54 includes the second absorptive material) toincrease in temperature. As the temperature of the first portion of thehousing 50 increases, the first portion of the housing 50 and/or a firstportion of the collar 120 (e.g., the first step 126) may melt to form afirst molten material. Similarly, as the temperature of the secondportion of the cell receptacle region cover 54 increases, the secondportion of the cell receptacle region cover 54 and/or a second portionof the collar 120 (e.g., the second step 128) may melt to form a secondmolten material. Accordingly, the first molten material may fill a firstgap between the collar 120 and the housing 50. Similarly, the secondmolten material may fill a second gap between the collar 120 and thecell receptacle region cover 54. In other embodiments, the first moltenmaterial may fill the first gap and/or the second gap, and the secondmolten material may also fill the first gap and/or the second gap.

At block 148, the first molten material may be cooled when the laser isno longer directed toward the third perimeter (e.g., when the laser hasfinished passing over the third perimeter and/or when the laser has beenturned off). Because the first molten material may fill the gap betweenthe collar 120 and the housing 50, the first molten material may causethe housing 50 to adhere to the collar 120 as the first molten materialre-hardens (e.g., re-solidifies). Similarly, the second molten materialmay also be cooled when the laser is no longer directed toward the thirdperimeter. Because the second molten material may fill the gap betweenthe collar 120 and the cell receptacle region cover 54, the secondmolten material may cause the cell receptacle region cover 54 to adhereto the collar 120 as the second molten material re-hardens (e.g.,re-solidifies). Accordingly, both the housing 50 and the cell receptacleregion cover 54 may be coupled to the collar 120. Moreover, any gaps oropenings between the housing 50, the cell receptacle region cover 54,and/or the collar 120 may be eliminated or substantially reduced.

One or more of the disclosed embodiments, alone or in combination, mayprovide one or more technical effects useful in the manufacture ofbattery modules, and portions of battery modules. In general,embodiments of the present disclosure include an improved laser weldingtechnique for creating a robust, substantially air-tight and/orwater-tight seal between a battery module housing and one or morecovers. In some cases, a collar may be utilized to couple the housing tothe one or more covers when a laser may not be transmitted through thehousing and/or the one or more covers. Forming a substantially air-tightand/or water-tight seal between the housing and the one or more coversmay enable the battery module to be protected from contaminants such aswater and dirt. The technical effects and technical problems in thespecification are exemplary and are not limiting. It should be notedthat the embodiments described in the specification may have othertechnical effects and can solve other technical problems.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

1-14. (canceled)
 15. A battery module, comprising: a housing comprisinga first absorptive material configured to absorb a laser emission; acover comprising a second absorptive material configured to absorb thelaser emission; and a collar coupled to the housing and coupled to thecover via a laser weld, wherein the collar comprises a transparentmaterial configured to transmit the laser emission through the collarand toward the housing and the cover, and wherein the laser weld isformed by a process comprising: disposing the cover over a receptacleregion of the housing; disposing the collar around a first perimeter ofthe housing and a second perimeter of the cover; directing a lasertoward a third perimeter of the collar such that the laser istransmitted through the transparent material and is absorbed by thefirst absorptive material and the second absorptive material; heatingthe first absorptive material and the second absorptive material suchthat a first portion of the first absorptive material increases intemperature and forms a first molten material and a second portion ofthe second absorptive material increases in temperature and forms asecond molten material; and cooling the first molten material and thesecond molten material to adhere the housing to the collar and adherethe cover to the collar.
 16. The battery module of claim 15, wherein thefirst molten material fills a first void between the housing and thecollar, and wherein the second molten material fills a second voidbetween the cover and the collar.
 17. The battery module of claim 16,wherein a seal between the housing, the cover, and the collar issubstantially air-tight and water-tight.
 18. The battery module of claim15, wherein the collar comprises a stepped geometry such that a firststep of the collar directly contacts the first perimeter of the housingand a second step of the collar directly contacts the second perimeterof the cover.
 19. A method for sealing a battery module, comprising:disposing a collar around a first perimeter of a housing and a secondperimeter of a cover; directing a laser toward a third perimeter of thecollar such that the laser is transmitted through a transparent materialof the collar and is absorbed by a first absorptive material of thehousing and a second absorptive material of the cover; heating the firstabsorptive material and the second absorptive material such that a firstportion of the first absorptive material increases in temperature andforms a first molten material and a second portion of the secondabsorptive material increases in temperature and forms a second moltenmaterial; and cooling the first molten material and the second moltenmaterial to adhere the housing to the collar and adhere the cover to thecollar.
 20. The battery module of claim 19, comprising passing the laserover the third perimeter between five and six times.
 21. The batterymodule of claim 19, comprising filling a first void between the housingand the collar with the first molten material and filling a second voidbetween the cover and the collar with the second molten material. 22.The battery module of claim 21, comprising sealing the housing, thecover, and the collar such that a substantially air-tight andwater-tight seal is formed.
 23. The battery module of claim 19, whereinthe first absorptive material or the second absorptive material comprisea polymeric material with an absorptive filler.
 24. The battery moduleof claim 19, wherein the transparent material comprises a polymericmaterial having a filler configured to structurally reinforce thecollar.